With the popularization and development of the Internet technology, multimedia technologies are increasingly used by Internet applications to render Web pages, in order to improve the user experience. A Web page generally contains many images. The size of most images is usually relatively small, for example, less than 1 Kb. In an example web page shown at the left side of FIG. 1, three images, “CHILD”, “MOUSE” and “PET”, are included. The three images, “CHILD”, “MOUSE” and “PET”, are represented by three files, for example, files “image1.gif”, “image2.gif” and “image3.gif” as shown at upper right of FIG. 1. To display the web page, the three image files will be individually referenced. Image resources are deployed on a server in the networks. When a client requests to the server for a web page, each image in the web page will initiate a HTTP link and occupy certain amount of network bandwidth. For each image, HTTP request and response header have to be processed and transmitted. Too many images in a web page would not only cost network bandwidth and influence transmission speed, but also increase the amount of work of the server.
US patent application (Publication No. 2004/0120589 A1) discloses a method for accelerating transmission of image data. According to the method, a network apparatus is set up between the remote client and the network server for converting the data received from the network server; then the changed data is transmitted to the remote client. The network apparatus transforms the image data into a smaller version of different format and with a decreased number of colors. Although the method can accelerate the transmission of image data, the quality of the image transmitted can be negatively influenced.